This study is a physical chemical study into the nature of the structure of the ribosomal subunits from the bacteria E. coli. The ribosomal proteins are isolated and characterized as to isolated physical properties. Solutions of mixtures of the proteins are subsequently analyzed principally by analytical ultracentrifugation techniques for molecular interactions. The thermodynamics of interaction are to be obtained in order to provide an interpretation of principal sites of interaction within the structure and types of interacting sites between the components. The study should reveal the network of interactions that may occur within the system. If the isolated interactions in solution persist in the total structure then a two dimensional energy versus pair member diagram can be utilized to construct a three dimensional diagram of the ribosomal structure. The study is examining the thermodynamics of interaction between the proteins S3-S4-S5 as a trimer from earlier studies, the thermodynamics of S8 self-association and its relationship to S5, the thermodynamics of systems containing S6, S18 and S21. In addition, the interaction between S7 and L12 is to be appraised. It is expected that the study will also examine the role of other factors in the protein synthesis mechanism for influence on the observed interactions as well as an examination of the interactions that occur between subunits.